Individuals are often faced with making a presentation to a large audience. It has become common to utilize a projector to project images of text and the like on a large screen that is viewable by the audience. The screen is often too large, or at a distance that is too far from the lecturer, to allow the lecturer to point to a particular area on the display with a physical device such as a long rod. This problem has been overcome by utilizing inexpensive hand held laser-based pointers that project a spot of light on the screen.
These devices utilize semiconductor lasers that are powered from an internal battery and have dimensions similar to that of an ordinary pencil. The laser pointer has the advantage of being able to project a spot on a screen located far from the lecturer. In fact, such pointers are also used for pointing out stars and other objects in the sky, as the beam can be seen as it is reflected off of dust or water droplets in the atmosphere. Unfortunately, small movements of the lecturer's hand translate into large movements of the light spot on the screen because the relatively large distance between the screen and the lecturer amplifies any shaking or other rotational movement of the hand. Hence, the point of light tends to move around the correct area on the screen. Such movement is distracting to the audience.
Laser pointers are also used to emphasize text or other areas of a display. For example, a lecturer can emphasize a particular word on a screen by rapidly moving the light spot back and forth under the word to underline the word. The lecturer may also circle a word by moving her hand such that the spot executes a circle on the screen. Such techniques require practice on the part of the lecturer to execute, and hence, are not easily executed by the occasional user. In addition, these higher functions can result in fatigue of the lecturer's hand muscles, since the beam must be moved with sufficient speed to give the impression of a stationary illumination pattern.